8250 vs 16550

8250 vs 16550

Post by Doug Owen » Thu, 20 Feb 2003 06:48:19

I'm digging through the bsp for the MVME 5110 to try to determine if the
COM1 and COM2 ports are
taking advantage of the FIFO's in the 16550 UARTS on the 5110.  As far as I
can tell it enables the FIFO but
at a threshold of 1 byte and it appears that only one character is read per
interrupt.  Has anyone else looked
into this - or tried to implement the FIFO's at a higher threshold?

Doug Owens


1. MS-Kermit 3.13, Windows, "Unknown hardware for port", 8250/16550 UART

        It's kind of difficult to guess here. Windows is controlling the
physical serial ports and presents virtualized images to Kermit. One item
needed by Kermit is the port i/o address (such as \x3f8), and Kermit obtains
that either from the Bios work area in segment 40h (first four words are
COM1...COM4 i/o addresses) or from the SET COMx Kermit command. If Windows
or your Pascal program clears the seg 40h area then Kermit will produce
this message. If Windows has the port allocated to some other task Windows
may report 0's in seg 40h. Looking down their with debug or other means
is a quick way to see what's happening.
        Does your Pascal program access the ports in any way?
        Source code for MSK 3.13 is available on kermit.columbia.edu,
cd kermit/a. If modified then the patch file won't work anymore.
        Joe D.

2. watchguard-SOHO <--VPN--> checkpoint

3. MSX 2 Philips 8250 HS/ Looking for out of order MSX 2 8250

4. Tandy 3100 model 10

5. programming the 16550 UART

6. MDI children

7. Intel 3.3 SerialPort driver recognizes a 16550 when a 16650 is present

8. ???

9. 16550 UART driver

10. 16550 UART driver and x86 BSP

11. UART 16550 FIFO usage

12. looking for a termios.c for 16550 UART

13. 16550 RS232 dirver for x86